1. Field of the Invention
The present invention relates to a display panel, and more particularly, to an advanced display panel which displays images using a plasma type of display.
2. Description of the Related Art
In general, display panels of a plasma method, which are called plasma display panels (PDP), display images using electric discharge. PDPs are widely popular due to their display performance, including superior luminance visual angle and other features.
PDPs are divided into a facing discharge type and a surface discharge type, depending on the location structure of the electrodes. Facing discharge type PDPs have a pair of sustaining electrodes which is disposed on an upper substrate and a lower substrate, and form an electric discharge in a direction perpendicular to the panel. Surface discharge type PDPs have a pair of sustaining electrodes which is disposed on the same substrate, and generates an electric discharge on one surface.
Facing discharge type PDPs have a high luminous efficacy, but suffer from the problem that phosphor is easily degraded by the electric discharge, thus, recently surface discharge type PDPs have become more widely used.
FIG. 1 shows the structure of a conventional PDP. The PDP in FIG. 1 is a surface discharge type PDP. In order to show the internal structure of the PDP more easily, the PDP is partially incised and an upper substrate 20 is rotated at a 90° angle.
A plurality of address electrodes 11 are disposed on the lower substrate 10 in a striped pattern and are buried by a first dielectric layer 12, which is white. A plurality of dams 13 are formed on the first dielectric layer 12 at predetermined intervals in order to prevent electrical and optical cross-talk between discharge cells 15. The insides of the discharge cells 15, which are partitioned by the plurality of dams 13, are coated with a phosphor layer 14 and are filled with discharge gas for plasma discharge. The discharge gas is a mixture of neon (Ne), Xenon (Xe) and other gases.
The upper substrate 20 is a transparent substrate through which visible light can penetrate, is made mainly of glass, and is sealed on the lower substrate 10 with the dams 13. Sustaining electrodes 21a and 21b are disposed in pairs under the upper substrate 20 and are perpendicular to the address electrodes 11. The sustaining electrodes 21a and 21b are made of transparent conductive material such as Indium Tin Oxide (ITO). To reduce line resistance of the sustaining electrodes 21a and 21b, bus electrodes 22a and 22b composed of metal are disposed under the sustaining electrodes 21a and 21b and have a narrower width than the sustaining electrodes 21a and 21b. The sustaining electrodes 21a and 21b and the bus electrodes 22a and 22b are buried by a second dielectric layer 23, which is transparent. A protection layer 24 is disposed under the second dielectric layer 23. The protection layer 24 prevents damage to the second dielectric layer 23 caused by sputtering of plasma particles, emits secondary electrons so as to lower discharge voltage and sustaining voltage, and is generally composed of magnesium oxide (MgO).
A plurality of black stripes 30 are disposed on the upper substrate 20 at predetermined intervals parallel to the sustaining electrodes 21a and 21b so as to prevent external light from entering the inside of the panel.
A wall charge is formed by generating an address discharge between one of the sustaining electrodes 21a and 21b and the address electrode 11, and then sustaining discharge is generated by the electric potential difference between the pair of sustaining electrodes 21a and 21b, so ultraviolet rays are generated by the discharge gas. The phosphor layer 14 is excited by the ultraviolet rays, causing visible light to be emitted. The visible light exits the upper substrate 20 and forms images which are perceptible to the user.
In such conventional PDPs, if the surroundings are brightly lit, for example, in a bright room, external light enters the discharge cells 15 or is reflected from the upper substrate 20 so that bright room contrast is reduced. Consequently, the image displaying performance of the PDP deteriorates.